Mileage: Purification
by jennytork
Summary: Still adjusting to life in Sam's body, Dean must undergo a rite to purify his system of the demon blood that now fills his veins, while Bobby looks for answers and finds only more questions, even as a few are finally answered.


PURIFICATION

"Man, right now I would _kill_ for a cheeseburger!" Dean leaned back in the chair, hands carding through his long bangs, trying to push them behind his ear.

Sam grinned from where he was leaning against the counter, nursing a bottle of beer. "With extra bacon or extra onions?"

"Yes!" Dean snapped. "Both!"

"You've only got two hours to go, son," Bobby said. "You're doin' fine." He slid him another water bottle.

Dean glared at it, then gave him a plaintive look. "Bobby, come on! I've drunk so much holy water my piss is startin' to sparkle!"

Then Dean yelled as he was sprayed by the beer Sam had just drunk.

Bobby was laughing at their antics, then he sobered. "Dean." A thrill of joy went through him as he got the reversed duo's names right – and had all day! "Dean, it's only 24 hours. You've done it for 22. You've two hours to go. Finish up and then I promise you I'll make you a cheeseburger. With extra bacon _and_ extra onions."

Dean studied him for a long moment, then he took the recycled water bottle, tipped it up, and drained half of the holy water in one long drink, closing his eyes against the brush of hair against his eyebrows.

When he finished, Sam was turning from one of the drawers. He held up a pair of scissors. "Want me to?"

Staring at the scissors, Dean's tongue darted out seemingly without his conscious control and caught a drop of water that was lurking in the corner of his mouth. "If I let you," he said slowly, "it's givin' up. It's tellin' me that this ain't gonna be undone."

"It ain't," Bobby said gently.

Sam came over and sat down in the chair beside Dean's. "We need to move forward," he said in that unsettling soft way that was liberally laced with steel. "Your visions – this purification you and Bobby've begun – all of it's tellin' us that. We need to move forward, Dean."

He met his brother's eyes. "With me as a psychic Sasquatch?"

"And me as a truncated smartass," Sam shot back.

Dean's lips twisted in a closed-mouth smile as he chuckled. "Bitch."

"Jerk," Sam shot back affectionately. He held up the scissors, head tilting and an eyebrow raising. "So?"

Dean sighed. "Gimme a minute to get a towel."

SPN MILEAGE SPN MILEAGE SPN

'Yeeesh, Dean, willya quit squirming already?"

Dean flinched, his eyes screwed shut. "It tickles!"

"Course it does, it's on your face. Touching you." Sam's fingertips brushed over Dean's tightly closed eyes and cheeks. "Okay, I'm done. Wanna see?"

"Yeah." Dean opened his eyes and stood up, heading for the mirror in the bathroom. He stopped short and just...stared. "...oh. Wow."

Sam's features looked back at him. He was still not used to that – it hadn't even been 48 hours yet.

His hair was shorter, curling slightly at the base of his skull. The long bangs that had brushed his cheekbones and eyegrows were shortened to a manageable length and slightly flared at the temples.

Dean turned his head, watching his eyes widen. "This is the style you had at Stanford."

"Yup, it's easiest to manage at that length. And since you're just learning to manage it..." Sam grinned at him, then the grin melted into a gentle smile. "Seriously, it's a way I can help you adjust."

Dean turned to look at him. "Well, tell me how I can help _you_ adjust!"

Sam lifted one shoulder in a shrug. "I'm fine." He watched Dean's jaw slide to one side and chuckled, shaking his head. "Seriously, I am."

"Know why I don't believe it?"

"Why don't you believe it?" Sam asked.

"Because now you know what I go through every moment of every day," Dean said. "You know about my-"

Sam cleared his throat. "Yeah," he said swiftly. "And it's a little unnerving. Now I know why you act the way you do. Coping mechanism."

"Which you're starting to use," Dean said.

"What're you talkin' about?" Bobby asked. "Boys," he said a little more firmly when both remained silent, staring at each other.

Dean nodded slowly, and Sam sighed, breaking eye contact and turning his head away.

"Sam," Bobby said. "What are you havin' to use a coping mechanism for?"

"My abilities...they're mental," Sam said. "Why in the hell Dean has them when they're in my head..."

"Mine were physical," Dean said slowly. "And now Sammy's gotta deal with 'em."

"Your abilities?" Bobby tilted his head. "What abilities?"

"Dad's training," Dean said, and Sam nodded. "It did something."

"They're not superhuman level," Sam cut in. "But his hearing and reflexes are better than normal. By a damn sight."

Bobby groaned softly, rubbing the bridge of his nose. "Dammit, John," he sighed.

Dean suddenly clapped his hands together. "So! Has it been 24 hours yet? I really, _really_ want that cheeseburger..."

SPN MILEAGE SPN MILEAGE SPN

Safe, full of cheeseburgers, and still reeling from their reversal of two days prior, Sam and Dean retired to bed somewhat early. Bobby surrounded himself with every tome he could think of, searching for purification rituals that required holy water ingestion for 24 hours. And rituals to purify from demon blood.

"You won't find anything," the same voice from earlier informed him. The same hand on his shoulder, preventing him from turning around.

"Why not?" Bobby demanded.

"It is an untried thing. It is a way to stop what is coming and save both the world – and them."

He took a deep breath. "So what's next in this...untried thing?"

A man's hand, clad in a tan trenchcoat sleeve, reached around and lay a pair of syringes down. One was full of yellowish-tinted clear liquid. The other was full of thick red liquid.

"Inject Dean with the clear one," the voice ordered. "It contains a chemical that will destroy the parts of his marrow that are replicating the demon-tainted blood and have since Sam was six months old."

"And the other?" Bobby gasped, half-curious and half-scared as to what the answer would be.

"The other is the keystone," the voice said. "The holy water prepared his body to reject the demon blood and accept this – the blood of an innocent. Freely given. Motivated by love. And the best part? It is Sam's infant blood."

Bobby drew in a sharp breath. "But Sam was infected at six months old! There is no way he could have consented-"

"He did not," the voice admitted. "Mary did. She surrendered her newborn's placenta to be used to aid others. The blood of an innocent. Freely given."

"Motivated by love," Bobby choked out, tears springing to his eyes. "Yeah - that's Mary all over."

"So it is human – but made holy from the love behind it," the voice said. "And since it is his own, Dean's body will not reject it."

"How will we know it's worked?" Bobby asked.

The voice held a grim note. "You will know it worked if his body begins to purge the demonic blood."

Bobby froze. "...purge? You mean he's-"

"I believe so. Yes."

Bobby flinched. "So tell me – who are you and why are you goin' to these lengths to help us?"

There was a long hesitation, then the hand squeezed his shoulder. "They are more important than you know. This is to derail their destiny and leave them free to do the jobs they have been chosen for without the horrible fates destiny has foretold for them. They will truly have free will after this. And besides." Was that a touch of humour in the voice? "They were both born on a Thursday. So they fall under my guardianship."

The hand was gone. Bobby turned, snarling, "Now I _know_ you're lyin!" He growled to find nobody there.

Fists clenching, he snarled under his breath, "Born on a Thursday? Both of them? Dean was born on Wednesday and Sam on Monday! What the hell did he-"

Bobby froze, his eyes going wide as he realised something. Slowly, he turned his head to the calendar hanging on the wall.

It was not yet midnight. It was still Saturday.

The body-switch had happened just a little over 48 hours prior.

As the clock chimed 11.30, Bobby found himself trembling as it sank in.

Sam and Dean – _as they were **now**_ – had, indeed, been "born" on a Thursday.

Bobby lunged for a book on the shelves. When he found what he was looking for, his legs buckled and he sat down on the couch with a deep sigh.

The guardian angel of Thursday existed. Every child born on a Thursday was his charge.

And his name was Castiel.

SPN MILEAGE SPN MILEAGE SPN

Bobby rarely, if ever, took things at face value. And there was no way in _hell_ he was going to pour something into Dean's body if he wasn't sure what it was.

Even if an angel had told him what it was.

So he drove into town, went to the hospital, and called in several favours. He left samples of the contents of both syringes – asking for a rush job if possible – and then drove back home.

The first reply came when he was laughing at the boys' antics. Dean was making burgers on the grill outside and Sam was inside the kitchen making a salad and they were bickering over the second vegetable. Dean wanted fries. Sam wanted baked potatoes.

Bobby had checked out of the argument long before, stating they were both potatoes and he'd be glad to have either one. Now, he was standing in the doorway laughing as the bickering threatened to degenerate into a food fight, when his phone rang. He checked the number.

Finding it to be one of his hospital friends, he moved into the research room and answered it. "So what did you find?"

His hand gripped the cell phone as he learned it was a new and potent chemotherapy drug. One more concentrated than his friend had ever seen. "I...see," Bobby said. "So it could destroy marrow, then." Hearing the affirmative answer, he asked, "What time frame would we be lookin' at, here? ...four to five hours? Damn, that's quick. ...Well, yeah, I guess as concentrated as it is... no, that's fine. It's just for information for my job. Thanks, man. I owe you one." He hung up and sighed, staring at the syringe on the table.

Now, he just had to wait for the results on the other one to come in. Then – and only then – would he break it to the boys.

He took a step toward the door and the phone went off again. He found it was his other friend. He answered it and asked, "What've you got for me, Jeannie?" He listened and then blew the air out of his cheeks. "I see. And could you get a DNA match?...Yeah, I'd love to-" His eyes closed. "You're sure about it. ...Okay, thanks. I owe you one. ...Yeah, see you later."

Bobby hung up and wiped a hand over his mouth and chin. Then he headed back out, finding they had compromised. There was a foil packet of fries happily griling away on one side of Dean's burgers, and two foil-wrapped potatoes grilling away on the other side.

Chuckling, he decided to talk to them after supper. That smelled too good to spoil.

SPN MILEAGE SPN MILEAGE SPN

After cleaning the grill and kitchen, Bobby took them into the research room. He showed them the syringes – and told them what the angel had told him.

Dean ran a hand through his hair, pushing it back a little. "So let me get this straight," he said. "The clear stuff will destroy the marrow that keep replicating the demon blood."

Bobby nodded, telling him the name of the drug. "It's new, and it's for chemotherapy. That's an ultra-concentrated form. It should do its work in 4 or 5 hours."

"Chemotherapy?" Dean gasped. He looked over at a visibly stunned Sam. "Huh. Guess the hair won't be a problem, then."

"You idjit, you're not gonna lose your hair," Bobby snarled. "It's too quick for that."

"Whose blood is that?" Sam asked, nodding at the second syringe.

Bobby sighed. "Yours." Then, remembering that it hadn't always been _Sam_ looking out of those suddenly stunned green eyes, he shook his head. "Dammit, can get used to anything... It's blood from the body you were born in."

"Dean's body, now," Sam said, the gravelly voice filling with ice. "Meaning, if what you said the angel said is true, it's full of demon blood."

"So we're back to square one," Dean sighed.

Bobby shook his head. "No, we're not. This is placental blood – given by your mother to help someone in need."

Both brothers drew in a shocked gasp. "But that means it's..." Dean gasped.

"The blood of an innocent," Sam breathed. "Freely given..."

"Motivated by love," Bobby finished. "It's holy, yeah. And that means-"

Dean was leaning forward now. "And that means it can cure me."

Sam nodded. "It can cure you of whatever the hell that demon did to me to make demon blood in your veins!" He paused, frowning. "And is it just me, or was that one effed-up series of pronouns in that sentence?"

Dean began to laugh. "Welcome to the rabbit hole, Alice!"

That set Sam to laughing, as Bobby just shook his head with a fond smile.

The smile fled as the laughter stopped and Dean picked up the clear syringe. He studied it for a few moments, then met Sam's eyes.

Without a word, he extended the hand holding the syringe toward his brother.

Without a word, Sam took it.

Dean shrugged out of the slightly too-small leather jacket he insisted on still wearing. He rolled up the sleeve of the plain yellow t-shirt.

And Bobby had to look away as Sam injected the body that used to be his with the first of the angel's syringes.

SPN MILEAGE SPN MILEAGE SPN

This, Dean was convinced, was hell.

It had been five hours since the injection, and he was on the bed, unable to do anything but curl up around his rolling stomach and quake with agony. His bones ached – burned – from the inside out. He'd been running a fever and he was so tired that he was convinced if he drifted off, he'd pull a Rip Van Winkle and not wake for 30 years.

It was a consolation, though, that he had not given in to the nausea.

After watching his brother suffer for three hours, Sam had had enough. He'd toed off his boots and crawled onto the narrow bed, folding his body around his brother's 6'4" frame in such a way that he could embrace his upper body. He brushed the sweaty hair matting on Dean's forehead away and murmured words of nonsense that were meant to comfort.

It was almost a relief to hear Bobby announce, "It's been five hours. Want me to-"

"I'll do it," Sam said.

Bobby hesitated. "Sam, you did the first one. I'm not sure Dean could be still enough for-"

"Bobby," Dean groaned through a spasm of pain. "I. Want. Sam. To. Do. It."

After a moment of silence, Bobby said, "Good enough for me." And he brought in the blood-filled syringe.

Sam slid up the sleeve and whispered, "Sorry about this."

"Yeah," Dean groaned. "Me, too."

The needle touched his arm and slid in. Sam pressed the plunger hard and fast, emptying every last drop into his brother in seconds.

And Dean screamed.

Bobby yelled as – something – shoved him through the doorway and slammed the door shut. A second later, a bolt of invisible energy – rippling like a sonic wave – passed through Bobby and knocked him off his feet.

He glanced around wildly, to find his furniture and books being shoved aside like a huge invisible toddler was having a temper tantrum. The noise of it was incredible.

But over it all, he could hear Sam yelling at Dean. He couldn't make out the words, but the boy sounded completely freaked out.

Suddenly, everything stopped. Hovering things crashed to the ground and Bobby got to his feet, yelling for Dean and Sam.

The door opened, and Sam stood there, blood dripping from a shallow would in his hairline. "Well," he said, the gravel in his voice deepening with his emotions, "_that_ was a rather nasty surprise. I'd forgotten that was rattling around in my psyche."

"Dean?" Bobby asked, head tilting.

"Passed out. Finally."

"Let's get you cleaned up." That's what they spent the next few hours doing – cleaning up.

As they worked, at one point, Bobby suddenly said, "Dean, could you hand me the-" He froze, and they looked at each other. "...dammit, Sam...I'm-"

"No, it's okay." Sam chuckled slightly. "Actually, we've been waitin' for that. I'm just sorry Dean missed it!"

"Missed what?" came from the doorway. Dean was leaning against the frame, pushing sweaty bangs off his forehead.

"Bobby called me Dean," Sam said with a grin.

Dean's new dimples cut furrows in his cheeks as he returned the grin. "Yeah? Sorry I missed that!"

"You're both idjits," Bobby growled. "How you doin'?"

Dean considered. "Feelin' a little stronger. I'm in less pain, that's for sure. Except for my stomach."

"Stomach?" Sam asked. "Still nauseous?" He walked over to Dean.

Bobby remembered what the angel had said. "Sam, you might wanna back off'a him."

"What? Why?" This was nearly spoken in unison.

"That angel fella said that his body was gonna purge the demon blood. The way things have gone, I'm not gonna be surprised if he-"

Dean's eyes went huge and a hand clamped over his mouth. He staggered toward the bathroom – but didn't make it.. He fell to his knees, his stomach forcibly evacuating itself onto Bobby's hall floor.

It was nothing but blood.

SPN MILEAGE SPN MILEAGE SPN

If there had ever been any doubt that what Dean was throwing up was pure demon blood, the fact that it dissolved when holy water hit it took care of that.

They maneouvred Dean back to the bed, where he curled into a miserable ball. Three hours later, he sat up gagging. He grabbed the wastebasket and emptied his stomach into it.

Again, it was all blood.

Again, it was easily dissolved.

Three hours later, it was the exact same routine. Wake up, gag, throw up copious amounts of demon blood. This time, however, Bobby measured it. "There's almost exactly a quart here."

"That's important how?" Dean groaned from his miserable curl, even as Sam burned the mess away with holy water.

"That's the maximum capacity of a human stomach," Sam said. "But why in the hell is it accumulating in your stomach, since it goes nowhere near the stomach in circulation?"

"This is demon blood, Sam," Bobby pointed out. "It's being purged. So maybe every time the new blood replicates, the demon blood flows into his stomach to be purged – the old-fashioned way."

Sam's nose wrinkled. "So once he throws up about 8 quarts, his body should have it purged?"

"Should," Bobby agreed. "Three down..."

"Five to go," Sam said, blinking and looking down where Dean had grabbed his wrist. "What is it?"

Dean was shaking, sweating. Every time he threw up, he would get all feverish. Now, his eyes fever-bright, he forced Sam's hand open and pressed his own palm against it.

"Dean?" Sam asked, visibly confused.

"Never realised...how small..." he whispered, his fingers closing over Sam's. "You really were a Sasquatch...and now..."

Sam smiled fondly at him. "I know." He disentangled his fingers. "You need to rest. Seriously. Rest."

But Dean's eyes remained stubbournly open, though they were trying to droop. Finally, Sam leaned in and whispered into the shell of his ear, "Dean. I'm here. You'll get through this, but you need to rest. I'm right here..." He threaded his fingers through Dean's now-larger ones. "See? I'm not goin' anywhere."

Weakly, the fingers squeezed. A soft sigh escaped Dean as his hazel eyes closed all the way.

Sam sat beside the bed, leaving his hand twined with his brother's. He knew the wait would be short – no more than two and a half hours at the most – before Dean would be awakened again by the gagging that preceded the next purge of his blood-filled stomach.

There would only be five more.

Sam could wait.

SPN MILEAGE SPN MILEAGE SPN

Ultimately, they had miscounted. There were 8 quarts of blood in a normal-sized human body. But Dean's new body was huge, and it ended up that he threw up eight more times instead of five.

The final time was a bit of blood among a lot of stomach acid and bile. Dissolving the blood, Bobby took the bag of mess out to the trash while Sam nursed Dean through the last of the fevers.

Bobby looked up at the overcast sky and asked it, "Is it over?"

"You have done it." The now-familiar voice said as a hand gripped his shoulder. "He is free of the taint of the demon's blood."

Bobby felt his eyes close in relief. "So – no more blasting my house apart? No more vision dreams?"

"Yes...and no. The visions were triggered by the taint – but not the ultimate cause of it. The telekinesis and - other abilities he would have developed – were caused by the taint."

Bobby stiffened. "Are you tellin' me these visions-"

"Are completely his. Yes. And now, Dean shall have to adjust to them."

"Change them back now. We've got them through the purification, you can-"

"It is necessary that they remain as they are."

"Why? What possible reason-"

"Advantages. Demons and witches will be expecting one – and will find the other."

Bobby shook his head. "I don't see how."

"You will."

"You saved their lives, then."

"Not yet. That depends on one action to come."

He felt his spine stiffen again. "What action?"

"I can not reveal that yet. But you will know." The hand lifted.

Bobby spun, and this time he caught sight of a mop of curly black hair and a tan trenchcoat fading away. "...huh." He couldn't be angry – much as he hated the crypticness and the hiding.

He couldn't be angry – because the angel had saved his boys from a hell that the demon blood would have caused them.

Bobby had no idea how accurate his thoughts would turn out to be.

SPN MILEAGE SPN MILEAGE SPN

The blond lay on his back, holding his stomach as he helplessly writhed in the grip of guffaws that rocked his body.

Dark eyes narrowed as the black-haired man watched him get himself under control. "It wasn't that funny."

"No sense of humour – always was your biggest failing." He laughed as he sat up. "He caught you! He turned too fast and _caught_ you!"

With a sound that might have been a snort, his companion turned his face away.

"So," the blond said, sitting up and smirking at him. "You intend to leave them wearing each other's skins?"

"I thought you, of all creation, would appreciate the – humour – in that."

"The humour, yes. The rationale behind it – no. There's more to it than playing a permanent prank on them, isn't it?"

Suddenly his companion couldn't meet his eyes.

"I thought so. Spill, Castiel. What is it? Why was this done?"

Silence stretched out for a long time, then dark eyes met lighter ones. The deep voice rang with the unmistakeable note of absolute truth. "One year, three months and two weeks from today, Armageddon begins with the breaking of the first seal."

That got the blond's full attention. "And you know this how?"

"I lived through it."

The blond's breath drew inward sharply.

"The first seal breaks when a righteous man who chooses hell is forced to torment people there. I intend to stop that."

"Why would a righteous man choose hell?"

Castiel's dark eyes narrowed again. "To save his brother."

"But who? How can we-" The blond froze. "It's one of them, isn't it?"

"And if he never has to save his brother – if he never chooses hell – then the seals remain unbroken for at least 300 more years, until the next pair of prophesied brothers arises."

"So you had me give you the power to switch them. And now you've purged the one Azazel tainted-" He suddenly tilted his head. "Azazel."

"Yes."

"He is still-"

"Yes."

"This isn't over."

"No."

"He could still choose-"

"Yes."

"How long do we have until we know?"

"Two weeks."

The blond chewed on his lip.

"Lay low for two weeks," Castiel said. "Until we know."

"And if he still chooses this fate?"

Castiel leaned back against the chair he was sitting in. "I'm praying that with the changes we've made – that will no longer be necessary."

"Laying low will be hard. What's in it for me if I do?"

The sound that came from the dark-haired angel was strange to the blond's ears. "Castiel? Did you just..._chuckle_?"

Castiel turned to look at him. "What's in it for you? If this works, you have several more years to tease them before they figure out who you are. If it doesn't - and things go to hell-"

"Literally," the blond interrupted.

"—then they figure out who you are in less than two. And you end up involved in all kinds of ways."

As the blond considered, Castiel added, "Plus – watching events play out with them in each other's skins might be a never-ending source of amusement."

"There is that!" the blond laughed.

The laughter ended in a shocked gasp as he was rewarded with the eerie sight of Castiel smiling – complete with a perfect row of upper teeth. "_Dude_," the blond said with a shudder. "Think I preferred the stoic look."

And this time there was no doubt whatsoever. That had definitely been a chuckle.

"What the hell happened to you in those three years that you're trying to change?" the blond whispered. "You're different. More...human."

"A charge became a friend," Castiel said. "And lost everything – more times than anyone should. I'm going to try to make it all right for him. For them."

END


End file.
